Hard Riddles: 48 Difficult Riddles with Answers (and Hints) on Riddlepedia
Funny & Tricky

Hard Riddles: 48 Difficult Riddles with Answers (and Hints)

48 riddles · tap Hint or Answer to reveal

by

These hard riddles are for people who are tired of riddles they solve in two seconds. There are 48 of them, sorted from medium to very hard, and the page ends with the 10 hardest riddles in the world: the famous logic puzzles that have stumped students, job candidates and puzzle fans for decades. Every math and logic answer has been worked out and double-checked, so when an answer surprises you, it’s still right.

Each riddle has a hint you can read first if you’re stuck, and the answer comes with a short explanation whenever the logic isn’t obvious. The riddles mix wordplay, lateral thinking, logic and math, and they’re all clean, so they work for teens, adults and sharp kids at a family table. Cover the answers with your hand, or read them out loud and give everyone one minute per riddle.

Medium Hard Riddles to Warm Up

I have a spine but no bones, a jacket but no arms, and I can tell you a whole story without ever opening my mouth. You have to open me instead. What am I?

Hint
You’ll find a lot of me in a library.
Answer
A book

I’m made almost entirely of holes, yet I can hold you up all afternoon between two trees. What am I?

Hint
You’d find me in a backyard or on a beach vacation, not in a bedroom.
Answer
A hammock

The more of me you take, the more of me you leave behind you. What am I?

Hint
Look behind you after a walk on a sandy beach.
Answer
Footsteps

I climb every mountain and cross every country, yet I never move an inch. What am I?

Hint
Cars and bikes travel along me.
Answer
A road

Read me forward or backward and I’m the same word. I’m the moment the sun stands highest and both hands of the clock point straight up. What am I?

Hint
The word has only four letters, and it begins and ends with the same one.
Answer
Noon

I can be broken without being touched, kept without being held, and made without any tools. What am I?

Hint
You give me when you say “I swear I’ll be there.”
Answer
A promise

Two painters can paint two walls in two hours. How many walls can four painters paint in eight hours?

Hint
First work out how long one painter needs for one wall.
Answer
16 walls. One painter paints one wall every two hours, so four painters paint four walls every two hours, and eight hours is four of those rounds.

The doctor gives you four pills and tells you to take one every 20 minutes. How many minutes will the pills last?

Hint
When do you take the very first pill?
Answer
60 minutes. You take the first one right away, then one at 20, 40 and 60 minutes.

A bat and a ball cost $1.10 together. The bat costs $1.00 more than the ball. How much does the ball cost?

Hint
The quick answer that pops into your head is wrong. Check it.
Answer
5 cents. The bat then costs $1.05, which is $1.00 more, and together they make $1.10. If the ball cost 10 cents, the bat would cost $1.10 and the total would be $1.20.

When I was 6 years old, my brother was half my age. Now I’m 40. How old is my brother?

Hint
The age gap between two brothers never changes.
Answer
  1. He was 3 when I was 6, so he is always 3 years younger.

What walks on four legs in the morning, on two legs at noon and on three legs in the evening?

Hint
The “day” is a whole lifetime, and one of the legs is made of wood.
Answer
A human. A baby crawls, an adult walks on two legs, and an old person walks with a cane. This is the famous riddle of the Sphinx from Greek myth.

Tom pushes his car along until he stops right in front of a hotel. The moment he gets there, he knows he’s bankrupt. What’s going on?

Hint
Tom’s car is very small, and so is the hotel.
Answer
He’s playing Monopoly. His car token landed on a property with a hotel, and he can’t pay the rent.

Hard Riddles with Answers

Spell me out in English and my letters are in perfect alphabetical order. I’m the only number like that. Which number am I?

Hint
I’m a multiple of ten, and I’m less than fifty.
Answer
Forty. F, O, R, T, Y are in alphabetical order. (Notice there’s no U in it, unlike “four.”)

Two days ago I was 9 years old. Next year I’ll turn 12. What’s today’s date, and when is my birthday?

Hint
Three birthdays have to fit between those two moments, so the dates must sit right at the edge of the year.
Answer
Today is January 1, and my birthday is December 31. Two days ago (December 30) I was 9. Yesterday I turned 10, this December I turn 11, and next December I turn 12.

How many times in one day do the hour hand and the minute hand of a clock point in exactly the same direction?

Hint
It’s not 24. The hands meet a little later every hour.
Answer
22 times. The minute hand catches up with the hour hand only 11 times every 12 hours, because between 11:00 and 1:00 they meet just once, at 12:00.

A drawer holds 10 black socks and 10 white socks, all mixed up. The room is pitch dark. How many socks must you take out to be sure you have two black ones?

Hint
Imagine you have the worst luck possible.
Answer
  1. In the worst case, the first 10 socks you grab are all white, and then the next 2 must be black.

You write out every whole number from 1 to 100. How many times do you write the digit 7?

Hint
Count the 7s in the tens place and the 7s in the ones place separately, and don’t forget 77.
Answer
  1. There are ten 7s in the ones place (7, 17, 27 … 97) and ten in the tens place (70 to 79).

A man rides into town on Friday. He stays for three nights and leaves on Friday. How is that possible?

Hint
“Friday” doesn’t have to be a day of the week.
Answer
His horse is named Friday.

Multiply together every digit on a phone keypad. What’s the answer?

Hint
One key ruins everything.
Answer
Zero. The keypad has a 0, and anything multiplied by 0 is 0.

How many squares of any size are there on a chessboard?

Hint
It’s a lot more than 64. Count the 2-by-2 squares, the 3-by-3 squares, and so on.
Answer
  1. There are 64 small squares, 49 of size 2x2, 36 of 3x3, 25, 16, 9, 4, and 1 big 8x8 square: 64 + 49 + 36 + 25 + 16 + 9 + 4 + 1 = 204.

Two trains start 100 km apart and drive toward each other at 50 km/h each. A bird starts at one train and flies at 75 km/h, back and forth between the trains, until they meet. How far does the bird fly?

Hint
Don’t follow the bird. Work out how long it’s in the air.
Answer
75 km. The trains close the gap at 100 km/h, so they meet after exactly one hour, and the bird flies for one hour at 75 km/h.

You sit on me. Take away my first letter and I grow on your head. Take away one more letter and you breathe me. What am I?

Hint
I have four legs, but I’m not an animal.
Answer
A chair. Chair, hair, air.

Count up from one in English (one, two, three …) and you’ll go a very long time before you write the letter B. What’s the first number that has a B in its name?

Hint
Hundreds, thousands and millions won’t do it.
Answer
One billion

Sam’s grandma is 74 years old, but she has only had 18 birthdays on her real birth date. How?

Hint
Her birthday isn’t on the calendar most years.
Answer
She was born on February 29, 1952. That date only comes in leap years, and there have been 18 of them since she was born (1956 to 2024).

Very Hard Riddles (Tricky)

Three ants sit on the three corners of a triangle. Each one picks a direction at random and walks along an edge toward another corner. What’s the chance that no two ants bump into each other?

Hint
The only safe plans are the ones where everybody goes the same way around.
Answer
1 in 4. There are 2 x 2 x 2 = 8 possible choices, and only 2 are safe: all clockwise or all counterclockwise. That’s 2 out of 8.

I’m a three-digit number. My tens digit is 5 more than my ones digit, and my hundreds digit is 8 less than my tens digit. What number am I?

Hint
A digit can’t be bigger than 9, so the tens digit doesn’t have many choices.
Answer
  1. The tens digit must be 9 (so the hundreds digit can be 1), which makes the ones digit 4.

Today is Sunday. What day of the week will it be 1,000 days from now?

Hint
Every 7 days you’re back to Sunday, so only the leftover days matter.
Answer
Saturday. 1,000 = 7 x 142 + 6, and 6 days after Sunday is Saturday.

At a party, every guest shook hands exactly once with every other guest. There were 45 handshakes in all. How many guests were there?

Hint
With n guests, each one shakes n - 1 hands, but every handshake involves two people.
Answer
10 guests. 10 x 9 / 2 = 45.

Mia has just as many brothers as sisters. Each of her brothers has twice as many sisters as brothers. How many children are in the family?

Hint
Mia doesn’t count herself as a sister, and each brother doesn’t count himself as a brother.
Answer
7 children: 4 girls and 3 boys. Mia has 3 sisters and 3 brothers. Each boy has 4 sisters and 2 brothers.

What number comes next: 2, 3, 5, 9, 17, …?

Hint
Look at how the gaps between the numbers grow.
Answer
  1. Each number is double the one before, minus 1 (17 x 2 - 1 = 33). The gaps also double: 1, 2, 4, 8, 16.

What letter comes next: M, V, E, M, J, S, U, …?

Hint
Look up at the night sky and travel away from the Sun.
Answer
N. They are the first letters of the planets in order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

There’s a coin in one of three boxes. Box 1 says “The coin is in here.” Box 2 says “The coin is not in here.” Box 3 says “The coin is not in box 1.” Exactly one label is true. Where is the coin?

Hint
Try putting the coin in each box and count how many labels come out true.
Answer
Box 2. Then label 1 is false, label 2 is false and label 3 is true. With the coin in box 1 or box 3, two labels would be true.

Think of any number. Double it, add 12, cut the result in half, then subtract the number you started with. What’s your answer?

Hint
Try it with two different starting numbers.
Answer
  1. Doubling and halving cancel out, so you’re left with your number plus 6, and then you take your number away.

A bag holds two coins: a normal one, and one with heads on both sides. You pull one out without looking, flip it, and it lands heads. What’s the chance you’re holding the two-headed coin?

Hint
Count the coin faces that could be showing right now, not the coins.
Answer
2 in 3. Three faces could be the heads you’re looking at: two belong to the two-headed coin and one belongs to the normal coin.

2026 began on a Thursday and isn’t a leap year. What’s the next year that will use exactly the same calendar, with every date on the same day of the week?

Hint
A normal year moves the calendar forward by one weekday, and a leap year moves it by two.
Answer
  1. From 2026 to 2037 the calendar shifts one weekday for each of the 8 normal years and two for each of the 3 leap years (2028, 2032, 2036): 14 days, exactly two weeks. And 2037 isn’t a leap year either.

You look at a clock in a mirror, and the clock seems to say 2:20. What time is it really?

Hint
A mirror flips the clock left to right, so the hands swap sides of the 12.
Answer
9:40. A mirrored time and the real time always add up to 12:00, and 2:20 + 9:40 = 12:00.

The pages of a book are numbered 1, 2, 3 and so on. Printing all the page numbers took 192 digits. How many pages does the book have?

Hint
Pages 1 to 9 use one digit each, and pages 10 to 99 use two.
Answer
100 pages. Pages 1 to 9 use 9 digits and pages 10 to 99 use 180, which makes 189. The last 3 digits are page 100.

Ella is 24. She is twice as old as her brother was when Ella was as old as her brother is now. How old is her brother?

Hint
Call the brother’s age B. The gap between them is 24 - B, and it never changes.
Answer
  1. Six years ago Ella was 18 (her brother’s age now), and her brother was 12. Today Ella is 24, which is twice 12.

The 10 Hardest Riddles in the World

You’re standing in front of two doors. One leads to freedom and the other to a maze you’ll never escape. A guard stands at each door. One guard always tells the truth and the other always lies, but you don’t know which is which. You may ask one guard one question. What do you ask?

Hint
Make the liar and the truth-teller point to the same door.
Answer
Ask either guard: “Which door would the other guard say leads to freedom?” Then take the other door. The liar lies about the honest answer, and the truth-teller honestly reports the lie, so both point to the wrong door.

A farmer must row a wolf, a goat and a cabbage across a river. His boat holds him and only one of them. Left alone together, the wolf eats the goat and the goat eats the cabbage. What must he carry first, and how many crossings does he need at the least?

Hint
At one point he has to bring something back with him.
Answer
The goat, in 7 crossings. Goat over, return alone, wolf over, bring the goat back, cabbage over, return alone, goat over.

You have two ropes and a lighter. Each rope takes exactly one hour to burn, but they burn unevenly, so half a rope doesn’t mean half an hour. How do you measure exactly 45 minutes?

Hint
A rope lit at both ends burns out twice as fast, no matter how uneven it is.
Answer
Light rope 1 at both ends and rope 2 at one end. When rope 1 burns out, 30 minutes have passed. Then light the other end of rope 2. It burns out 15 minutes later, making 45.

Four friends must cross a rickety bridge at night with one flashlight. The bridge holds two people at a time, and anyone crossing needs the flashlight. They cross in 1, 2, 7 and 10 minutes, and a pair walks at the slower one’s speed. What’s the shortest total time to get everyone across?

Hint
Send the two slowest friends across together, so their times overlap.
Answer
17 minutes. 1 and 2 cross (2), 1 returns (1), 7 and 10 cross (10), 2 returns (2), 1 and 2 cross (2): 2 + 1 + 10 + 2 + 2 = 17.

Ann, Ben and Cal stand in a line, all facing forward. Cal, at the back, can see Ben and Ann. Ben can see only Ann. Ann can’t see anyone. They know their hats came from a bag of 3 red hats and 2 white hats. Cal says, “I don’t know my hat’s color.” Then Ben says, “I don’t know mine either.” Ann says, “I know mine!” What color is Ann’s hat?

Hint
Ask what Cal would have said if he’d seen two white hats in front of him.
Answer
Red. Cal would know his hat is red if Ben and Ann both wore white, so at least one of them is red. If Ann’s hat were white, Ben would then know his own is red. Ben didn’t know, so Ann’s hat must be red.

Four houses stand in a row, numbered 1 to 4 from left to right. Each has a different color (red, blue, green, yellow), owner (Ada, Ben, Cy, Dee) and pet (cat, dog, fish, bird). The red house is house 1. Ada lives in the blue house. The green house is directly to the right of the blue house. The dog lives in the red house. Ben lives in house 4. The cat lives next door to Ada. Cy owns the bird. Who owns the fish?

Hint
Try the blue house in each possible spot and see where Cy and the bird can go.
Answer
Ada. The blue house can’t be house 2, because then Cy and the bird would have no house left. So blue is house 3 and green is house 4. Cy must be in house 2 with the bird, the cat is with Ben in house 4, and the fish is with Ada in house 3.

You have two identical eggs and a 36-floor building. Below a certain floor an egg survives the drop, and from that floor up it breaks. What’s the fewest drops that always lets you find that floor?

Hint
Once the first egg breaks, the second must test floors one by one, so make each jump one floor shorter than the last.
Answer
8 drops. Drop the first egg from floors 8, 15, 21, 26, 30, 33, 35 and 36. If it breaks, test the floors in the gap one at a time with the second egg. Each plan takes 8 drops at most, because 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = 36.

You’re blindfolded at a table with 40 coins. Exactly 7 are heads up, and you can’t feel which. How do you split the coins into two piles with the same number of heads in each?

Hint
You’re allowed to flip coins over, and the small pile should be a very specific size.
Answer
Slide any 7 coins into a new pile and flip all 7. If that pile had h heads, the big pile has 7 - h heads, and after flipping, the small pile also has 7 - h heads.

What number comes next: 1, 4, 9, 61, 52, 63, …?

Hint
The first three numbers are perfect squares. What if the next ones are written backward?
Answer
  1. These are the squares 1, 4, 9, 16, 25, 36 written backward, and the next square, 49, becomes 94.

A hallway has 200 closed lockers and 200 students. Student 1 opens every locker. Student 2 closes every 2nd locker. Student 3 changes every 3rd locker (opening it if closed, closing it if open), and so on, until student 200 changes only locker 200. How many lockers are open at the end?

Hint
A locker ends up open only if it was changed an odd number of times. Which numbers have an odd number of divisors?
Answer
  1. Only perfect squares have an odd number of divisors, so the open lockers are the squares 1, 4, 9, 16 and so on, up to 196 (14 x 14).

How to Run a Hard Riddle Challenge

Turn these hard riddles into a game by splitting players into teams and giving each riddle a point value: 1 point for the warm-ups, 2 for the hard riddles, 3 for the very hard ones and 5 for each of the 10 hardest riddles in the world. Set a timer (one minute for wordplay, three to five minutes for the logic puzzles) and let any team “buy” the hint for half the points. Paper and pencil are allowed for the math, but phones aren’t.

For a classroom or a team meeting, post one of the hardest riddles on the board each morning and reveal the answer at the end of the day. The guard, the river crossing and the hat puzzle are great for showing how to reason step by step, because the explanation is as satisfying as the answer.

Want more? Try our logic riddles, these math brain teasers or our clean, tricky riddles for adults.